There are disclosed in the prior art a number of inks. These compositions are generally used in printing press operations and writing instruments such as pens and markers. These compositions are often termed either permanent or non-permanent. Generally, permanent inks comprise, in part, organic solvent soluble materials while typical non-permanent inks are water soluble. A resistance to light and air is also a factor for permanent inks. An ink that is not water soluble, but fades quickly in light is not permanent. However, some water based binders combined with earth or charcoal pigments used for cave paintings have withstood the test of ages.
Inks generally are mixtures of a coloring matter dispersed or dissolved in a carrier fluid. The coloring matter, if readily dissolved in the carrier fluid is termed a dye. An insoluble coloring material is termed a pigment. Pigments generally are finely ground solid materials. The nature and amount of pigment or dye contained in an ink composition determines its color.
In the past, inks have been used to make prints of an original composition by use of stencil printing, block printing (relief printing), screen printing, lithographic printing or intaglio printing. Screen printing requires a great deal of equipment, such as screen frames, squeegees, and resist materials. Relief printing requires gouges and cutting tools, wood, linoleum, or vinyl plates, inking rolls (brayers), printing inks, and often printing presses.
Intaglio printing of an ink composition from the recessed surfaces of metal or plastic printing plates (etchings and engravings) require such skills and equipment that it is rarely used even in high school level art classes.
In addition to the obvious difficulties of children making use of these types of printing processes such as the high degree of skill and dexterity needed, children also would find it difficult to produce prints having multiple colors. Obviously, the play value children gain from being able to use various colors, such as those available from crayons and markers used by children, is highly desirable and a printing system for children should be capable of yielding multi-color prints or reproductions.
The difficulties presented by these various reproduction methods may be overcome by the use of sheets of material such as paper or plastic which are coated with an ink which may be transferred to a second medium such as paper.
Printing sheets which may be adhered to a support and are used in relief or intaglio printing are described in U.S. Pat. No. 3,263,605 which is assigned to Minnesota Mining and Manufacturing Company. These sheets were like a thick rubber block in composition.
For a period of time, Minnesota Mining and Manufacturing sold water soluble printing sheets which were of high solubility and which were coated from solution rather than a hot melt. However, these sheets were ultimately unsuccessful because the inks used were highly water soluble and individual sheets coated with the ink would stick together at high humidities without a suitable separator sheet. In addition, these sheets were very difficult to use when printing onto wet and highly absorbent paper sheets since much of the ink would dissolve and a sheet coated with the ink could yield very few prints as a result of the ink going into solution. Further, as a result of the ink going into solution, smeared prints were often produced and clearly defined images were difficult, if not impossible, to produce. Also, greater pressure than can be produced by the hand of a child was required to make a print with these sheets.
Also, the Minnesota Mining and Manufacturing sheets required a wet coating and drying process for manufacture; an expensive process which requires expensive base papers for the printing sheets because they must withstand large lateral forces while being pulled wet through long drying ovens.
It is, therefore, an object of the present invention to provide an ink composition which may be used to produce multiple prints or copies,
It is also an object of the present invention to produce a printing sheet for easy use by children requiring minimal, commonly available, and safe tools.
A further object of the invention is to provide ink for use on a printing sheet which are washable and non-toxic.
A further object of the invention is to provide ink compositions which are water soluble, while still having a low tack or adhesion level to wet paper, and which do not block or stick to each other at 100% Relative Humidity.
It is also an object of the invention to simplify printmaking such that it can be performed in the home or classroom in an economical manner, especially by children.
It is also an object of the present invention to produce a printing sheet onto which has been coated an ink composition of the invention.
A still further object of the invention is to provide printing sheets capable of releasing controlled amounts of an ink composition, even onto very wet and absorbent papers, without smearing or bleeding.
Another object of the present invention is to provide ink films with sufficient flexibility and adhesion to a printing sheet backing to resist flaking, cracking and falling off when the films are flexed, handled and incised.
An additional object of the present invention is to provide ink films which are inherently economical and stimulate creativity because the cut pieces may assembled into finished prints and scrap pieces may generally be used resulting in a printing plate much larger than the original piece as opposed to wood or linoleum block printing plates or silk screen stencils where the artist removes part of the printing medium which cannot be further used.
A further object of the present invention is to provide ink films which can be given additional detailing by incising or engraving away the ink composition with a pencil or other suitable sharp object, or by covering the ink composition with a water insoluble resist, such as a common wax crayon, grease pencil, liquid wax or a candle.
Another object of the present invention is to provide a printing sheet having a layout drawn with pencil or pen on the paper side of the ink sheets, thereby reducing the mess of working directly on the surface having the ink composition and the ink composition pieces are right-reading, not the mirror images required when working from the ink composition side of the sheets.
It is also an object of the present invention to provide various printing sheets respectively coated with various colors of the ink composition of the invention which may have various figures or shapes cut from each of the sheets which can then be combined on a master plate to enable the printing of a multi-colored print.
Finally, an object of the present invention is to permit intaglio type printing to be easily performed by covering the ink film with crayon and scratching through the crayon to the ink composition with a pencil, and printing by hand pressure or with a soft rubber roller.